Polarizing film laminate comprising a long polarizing having exposed portion where a polarizer is exposed

ABSTRACT

A long polarizing film laminate capable of producing a polarizer that can achieve the multi-functionalization and high-functionalization of an electronic device, such as an image display apparatus, that shows no variation in quality when provided as a final product, and that is excellent in yield in its production. A polarizing film laminate according to an embodiment of the present invention includes: a long polarizer; and a surface protective film arranged on one surface side of the polarizer. The polarizing film laminate has, on the one surface side, exposed portions where the polarizer is exposed. The exposed portions are arranged in a lengthwise direction and/or a widthwise direction of the polarizer at predetermined intervals.

TECHNICAL FIELD

The present invention relates to a long polarizing film laminate. Morespecifically, the present invention relates to a laminate of a polarizerand a surface protective film.

BACKGROUND ART

Some of the image display apparatus of a cellular phone, a notebookpersonal computer (PC), and the like have mounted thereon internalelectronic parts, such as a camera. Various investigations have beenmade for the purpose of improving, for example, the camera performanceof any such image display apparatus (for example, Patent Literatures 1to 7). However, an additional improvement in camera performance or thelike has been desired in association with rapid widespread use of asmart phone and a touch panel-type information processing apparatus. Inaddition, a polarizing plate partially having polarization performancehas been required in order to correspond to the diversification of theshapes of the image display apparatus and the high-functionalizationthereof. In order that those requirements may be satisfied industriallyand commercially, it has been desired that the image display apparatusand/or a part thereof be produced at acceptable cost. However, thereremain various matters to be investigated for establishing suchtechnology.

CITATION LIST Patent Literature

[PTL 1] JP 2011-81315 A

[PTL 2] JP 2007-241314 A

[PTL 3] US 2004/0212555 A1

[PTL 4] KR 10-2012-0118205 A

[PTL 5] KR 10-1293210 B1

[PTL 6] JP 2012-137738 A

[PTL 7] US 2014/0118826 A1

SUMMARY OF INVENTION Technical Problem

The present invention has been made to solve the above-describedproblems, and a primary object of the present invention is to provide along polarizing film laminate capable of producing a polarizer that canachieve the multi-functionalization and high-functionalization of anelectronic device, such as an image display apparatus, that shows novariation in quality when provided as a final product, and that isexcellent in yield in its production.

Solution to Problem

A polarizing film laminate according to an embodiment of the presentinvention includes: a long polarizer; and a surface protective filmarranged on one surface side of the polarizer. The polarizing filmlaminate has, on the one surface side, exposed portions where thepolarizer is exposed. The exposed portions are arranged in a lengthwisedirection and/or a widthwise direction of the polarizer at predeterminedintervals.

In one embodiment of the present invention, the exposed portions arearranged in the lengthwise direction at predetermined intervals.

In one embodiment of the present invention, the exposed portions arearranged in at least the lengthwise direction at substantially equalintervals.

In one embodiment of the present invention, the exposed portions arearranged in the lengthwise direction and the widthwise direction of thepolarizer at substantially equal intervals.

In one embodiment of the present invention, when the polarizer is cutinto a predetermined size to be mounted on an image display apparatushaving a predetermined size, the exposed portions are each arranged at aposition corresponding to a camera portion of the image displayapparatus.

In one embodiment of the present invention, a direction of a straightline connecting the exposed portions adjacent to each other falls withina range of ±10° with respect to the lengthwise direction and/or thewidthwise direction of the polarizer.

In one embodiment of the present invention, the polarizer has athickness of 10 μm or less.

In one embodiment of the present invention, portions of the polarizercorresponding to the exposed portions each have a polarization degree of99.9% or more.

In one embodiment of the present invention, the polarizing film laminateis subjected to a step of decoloring the portions of the polarizercorresponding to the exposed portions while being conveyed in thelengthwise direction.

In one embodiment of the present invention, portions of the polarizercorresponding to the exposed portions include non-polarization portionsformed by decoloring the polarizer.

In one embodiment of the present invention, the non-polarizationportions each have a transmittance of 90% or more.

In one embodiment of the present invention, the portions of thepolarizer corresponding to the exposed portions each include a recessedportion having a recessed surface on the one surface side of thepolarizer.

In one embodiment of the present invention, the non-polarizationportions include low concentration portions each having a content of thedichromatic substance lower than that of any other portion.

In one embodiment of the present invention, a content of an alkali metaland/or an alkaline earth metal in each of the low concentration portionsis 3.6 wt % or less.

In one embodiment of the present invention, the low concentrationportions are formed by bringing a basic solution into contact with thepolarizer.

In one embodiment of the present invention, the basic solution includesan aqueous solution containing a hydroxide of an alkali metal and/or analkaline earth metal.

In one embodiment of the present invention, the surface protective filmhas formed therein through-holes, and portions corresponding to thethrough-holes comprise the exposed portions.

In one embodiment of the present invention, the surface protective filmis laminated on the polarizer in a peelable manner.

In one embodiment of the present invention, the polarizing film laminatefurther includes a protective film arranged on another surface side ofthe polarizer.

In one embodiment of the present invention, the protective film has athickness of 80 μm or less.

In one embodiment of the present invention, the polarizing film laminatefurther includes a second surface protective film arranged on anothersurface side of the polarizer.

In one embodiment of the present invention, the exposed portions arearranged in a dotted manner.

In one embodiment of the present invention, a plan-view shape of each ofthe exposed portions includes a substantially circular shape or asubstantially rectangular shape.

In one embodiment of the present invention, the polarizing film laminateis wound in a roll shape.

In one embodiment of the present invention, the polarizing film laminateis used for producing a plurality of polarizers each having anon-polarization portion.

Advantageous Effects of Invention

According to the present invention, the polarizing film laminateincluding a long polarizer and a surface protective film arranged on onesurface side of the polarizer, the polarizing film laminate having, onthe one surface side, exposed portions where the polarizer is exposed,the exposed portions being arranged in the lengthwise direction and/orwidthwise direction of the polarizer at predetermined intervals (i.e.,according to a predetermined pattern), is provided. Such polarizing filmlaminate can be satisfactorily subjected to, for example, a chemicaltreatment, and hence a polarizer having non-polarization portionsarranged according to a predetermined pattern can be produced withextremely high production efficiency. In such polarizer, the positionsof the non-polarization portions can be set in accordance with the sizeof a polarizer to be cut and mounted on an image display apparatus andthe position of a camera portion of the image display apparatus.Accordingly, a yield at the time of the production of a polarizer havinga predetermined size is extremely excellent. Further, the positions ofthe non-polarization portions can be accurately set, and hence theposition of a non-polarization portion in the polarizer having apredetermined size to be obtained can also be satisfactorily controlled.Therefore, a variation in position of a non-polarization portion betweenthe polarizers each having a predetermined size to be obtained becomessmaller, and hence final products (polarizers each having apredetermined size) free of variation in quality can be obtained. As aresult, the polarizing film laminate of the present invention cancontribute to the multi-functionalization and high-functionalization ofan electronic device, such as an image display apparatus. Further,according to the polarizing film laminate of the present invention, apositional relationship between a non-polarization portion and anabsorption axis can be controlled in the entirety of the long polarizerin a unified manner, and hence a final product excellent in axialaccuracy (and hence excellent in optical characteristics) can beobtained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic perspective view of a polarizing film laminateaccording to one embodiment of the present invention.

FIG. 2 is a partial sectional view of the polarizing film laminateillustrated in FIG. 1.

FIG. 3A is a schematic plan view for illustrating an example of thearrangement pattern of exposed portions in the polarizing film laminateaccording to the embodiment of the present invention.

FIG. 3B is a schematic plan view for illustrating another example of thearrangement pattern of exposed portions in the polarizing film laminateaccording to the embodiment of the present invention.

FIG. 3C is a schematic plan view for illustrating still another exampleof the arrangement pattern of exposed portions in the polarizing filmlaminate according to the embodiment of the present invention.

FIG. 4 is a schematic perspective view for illustrating the laminationof a polarizer and a surface protective film in a method of producing apolarizing film laminate according to an embodiment of the presentinvention.

FIG. 5 is a schematic view for illustrating the formation ofnon-polarization portions in the polarizing film laminate according tothe embodiment of the present invention.

FIG. 6(a) is a graph for showing the result of the evaluation of surfacesmoothness in Example 1, and FIG. 6(b) is a graph for showing the resultof the evaluation of surface smoothness in Example 2.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention are described below. However, thepresent invention is not limited to these embodiments.

A. Polarizing Film Laminate

FIG. 1 and FIG. 2 are each a schematic view of a polarizing filmlaminate according to one embodiment of the present invention. FIG. 1 isa perspective view of the polarizing film laminate, and FIG. 2 is apartial sectional view of the polarizing film laminate illustrated inFIG. 1. A polarizing film laminate 100 includes: a polarizer 10; asurface protective film 20 arranged on one surface side of the polarizer10 (an upper surface side in the illustrated example); and a protectivefilm 30 and a second surface protective film 40 arranged on the othersurface side of the polarizer 10 (a lower surface side in theillustrated example). The polarizing film laminate 100 has, on the onesurface side (the upper surface side in the illustrated example),exposed portions 11, 11, . . . where the polarizer 10 is exposed. In theillustrated example, the exposed portions 11 are arranged by formingthrough-holes 21 in the surface protective film 20 arranged on the onesurface side of the polarizer 10 (the surface protective film having thethrough-holes may be referred to as “first surface protective film” forconvenience). The portions of the polarizer 10 corresponding to theexposed portions 11 may be turned into non-polarization portions by anyappropriate treatment.

The surface protective film 20 is used for the purpose of temporarilyprotecting the polarizer 10 at the time of the production of a polarizerhaving non-polarization portions, and is removed from the polarizer 10at any appropriate timing. Therefore, the surface protective film 20 islaminated on the polarizer 10 in a peelable manner. The surfaceprotective film 20 is typically bonded to the polarizer 10 throughintermediation of any appropriate pressure-sensitive adhesive, thoughthe pressure-sensitive adhesive is not shown. The simple term“protective film” as used herein means a polarizer protective film likethe protective film 30, and is different from the surface protectivefilm to be temporarily used at the time of the production.

The polarizer 10 is long, and the polarizing film laminate 100 istypically wound in a roll shape as illustrated in FIG. 1. The term“long” as used herein means an elongated shape in which a length issufficiently long as compared to a width, and includes, for example, anelongated shape in which a length is 10 or more times, preferably 20 ormore times as long as a width. In the illustrated example, thelengthwise direction of the long surface protective film 20 and thelengthwise direction of the polarizer 10 are substantially parallel toeach other. In one embodiment, the width dimension of the long surfaceprotective film 20 is designed so as to be substantially equal to, orlarger than, the width dimension of the polarizer 10.

The exposed portions 11 are arranged in the lengthwise direction and/orwidthwise direction of the polarizer 10 at predetermined intervals(i.e., according to a predetermined pattern). The arrangement pattern ofthe exposed portions 11 may be appropriately set in accordance withpurposes. When the polarizer 10 is cut (e.g., cut in the lengthwisedirection and/or the widthwise direction, or punched) into apredetermined size to be mounted on an image display apparatus having apredetermined size, the exposed portions 11 are each typically arrangedat a position corresponding to a camera portion of the image displayapparatus.

When polarizer pieces having only one size are obtained from the onelong polarizer 10 by cutting, the exposed portions 11 may be arranged atsubstantially equal intervals in each of the lengthwise direction andwidthwise direction of the polarizer 10 as illustrated in FIG. 1.According to such construction, the cutting of the polarizer into thepredetermined size in accordance with the size of the image displayapparatus is easily controlled, and hence a yield can be improved.Further, a variation in position of a non-polarization portion (exposedportion) between the cut sheets of the polarizer (polarizing filmlaminate) can be suppressed. The phrase “substantially equal intervalsin each of the lengthwise direction and widthwise direction” means thatintervals in the lengthwise direction are equal to each other andintervals in the widthwise direction are equal to each other, and it isnot necessary that the intervals in the lengthwise direction and theintervals in the widthwise direction be equal to each other. Forexample, when the intervals in the lengthwise direction are eachrepresented by L1, and the intervals in the widthwise direction are eachrepresented by L2, the L1 may be equal to the L2, or the L1 may not beequal to the L2. In addition, the term “polarizer pieces” meanspolarizers obtained by cutting the long polarizer. Herein, the polarizerpieces may be simply referred to as “polarizers” contextually.

When polarizer pieces having a plurality of sizes are obtained from theone long polarizer 10 by cutting, the intervals between the exposedportions 11 in the lengthwise direction and/or widthwise direction ofthe polarizer 10 may be changed in accordance with the sizes of thepolarizers to be cut out of the long polarizer. For example, the exposedportions 11 may be arranged at substantially equal intervals in thelengthwise direction and arranged at different intervals in thewidthwise direction, or may be arranged at different intervals in thelengthwise direction and arranged at substantially equal intervals inthe widthwise direction. When the exposed portions 11 are arranged atdifferent intervals in the lengthwise direction or the widthwisedirection, all of intervals between adjacent exposed portions may bedifferent, or only part of the intervals (intervals between specificadjacent exposed portions) may be different. In addition, the followingmay be performed: a plurality of regions are specified in the lengthwisedirection of the polarizer 10, and the intervals between the exposedportions 11 in the lengthwise direction and/or the widthwise directionare set for each of the regions. As described above, one feature of thepresent invention lies in that in the long polarizer, the exposedportions (non-polarization portions) can be formed according to anyappropriate arrangement pattern in accordance with purposes.

FIG. 3A is a schematic plan view for illustrating an example of thearrangement pattern of the exposed portions in the polarizing filmlaminate according to the embodiment of the present invention, FIG. 3Bis a schematic plan view for illustrating another example of thearrangement pattern of the exposed portions, and FIG. 3C is a schematicplan view for illustrating still another example of the arrangementpattern of the exposed portions. In one embodiment, the exposed portions11 are arranged so that, as illustrated in FIG. 3A, a straight lineconnecting the exposed portions 11 adjacent to each other in thelengthwise direction of the polarizer 10 may be substantially parallelto the lengthwise direction, and a straight line connecting the exposedportions 11 adjacent to each other in the widthwise direction of thepolarizer 10 may be substantially parallel to the widthwise direction.This embodiment corresponds to the arrangement pattern of the exposedportions 11 in the polarizing film laminate 100 illustrated in FIG. 1.In another embodiment, the exposed portions 11 are arranged so that, asillustrated in FIG. 3B, the straight line connecting the exposedportions 11 adjacent to each other in the lengthwise direction of thepolarizer 10 may be substantially parallel to the lengthwise direction,and the straight line connecting the exposed portions adjacent to eachother in the widthwise direction of the polarizer 10 may have apredetermined angle θ_(W) with respect to the widthwise direction. Instill another embodiment, the exposed portions 11 are arranged so that,as illustrated in FIG. 3C, the straight line connecting the exposedportions adjacent to each other in the lengthwise direction of thepolarizer 10 may have a predetermined angle θ_(L) with respect to thelengthwise direction, and the straight line connecting the exposedportions adjacent to each other in the widthwise direction of thepolarizer 10 may have the predetermined angle θ_(W) with respect to thewidthwise direction.

The θ_(L) and/or the θ_(W) are each/is preferably more than 0° and ±10°or less. Here, the symbol “±” means that both clockwise andcounterclockwise directions with respect to a reference direction (thelengthwise direction or widthwise direction of the polarizer) areincluded. Each of the embodiments illustrated in FIG. 3B and FIG. 3C hassuch an advantage as follows. In some image display apparatus, theabsorption axis of a polarizer may be required to be arranged whilebeing shifted by up to about 10° with respect to the long side or shortside of each of the apparatus for improving its display characteristics.As described later, the absorption axis of the polarizer is expressed inthe lengthwise direction or the widthwise direction. Accordingly,according to such construction as described above, in such cases, thedirections of the absorption axes of sheets of polarizing film laminates(polarizers) 101 cut out of the polarizing film laminate 100 can each beprecisely controlled to a desired angle, and a variation in absorptionaxis direction between the polarizing film laminates (polarizers) 101can be significantly suppressed. Needless to say, the arrangementpattern of the exposed portions is not limited to the illustratedexamples. For example, the exposed portions may be arranged so that thestraight line connecting the exposed portions adjacent to each other inthe lengthwise direction of the polarizer may have the predeterminedangle θ_(L) with respect to the lengthwise direction, and the straightline connecting the exposed portions adjacent to each other in thewidthwise direction of the polarizer may be substantially parallel tothe widthwise direction. In addition, the following may be performed: aplurality of regions are specified along the lengthwise direction of thepolarizer, and the θ_(L) and/or the θ_(W) are/is set for each of theregions.

Any appropriate shape may be adopted as the plan-view shape of each ofthe exposed portions 11 (shape when viewed from the one surface side ofthe polarizing film laminate 100) as long as the shape does notadversely affect the camera performance of an image display apparatus inwhich the polarizer from the laminate is used. The plan-view shape ofeach of the exposed portions is, for example, a substantially circularshape or a substantially rectangular shape. Specific examples thereofinclude a circular shape, an elliptical shape, a square shape, arectangular shape, and a diamond shape. Exposed portions each having adesired plan-view shape can be formed by appropriately setting theshapes of the through-holes of the surface protective film to bedescribed later.

A-1. Polarizer

The polarizer 10 typically includes a resin film containing adichromatic substance. The resin film is, for example, a polyvinylalcohol-based resin (hereinafter referred to as “PVA-based resin”) film.

Examples of the dichromatic substance include iodine and an organic dye.The substances may be used alone or in combination. Of those, iodine ispreferably used. This is because of the following reason: for example,when non-polarization portions are formed by decoloring based on achemical treatment, an iodine complex in the resin film (polarizer) isappropriately reduced, and hence non-polarization portions each havingsuch characteristics as to be appropriate for use in a camera portioncan be formed.

Any appropriate resin may be used as a PVA-based resin forming thePVA-based resin film. Examples of the PVA-based resin include polyvinylalcohol and an ethylene-vinyl alcohol copolymer. The polyvinyl alcoholis obtained by saponifying polyvinyl acetate. The ethylene-vinyl alcoholcopolymer is obtained by saponifying an ethylene-vinyl acetatecopolymer. The saponification degree of the PVA-based resin is typicallyfrom 85 mol % to 100 mol %, preferably from 95.0 mol % to 99.95 mol %,more preferably from 99.0 mol % to 99.93 mol %. The saponificationdegree may be determined in conformity with JIS K 6726-1994. The use ofthe PVA-based resin having such saponification degree can provide apolarizer excellent in durability. When the saponification degree isexcessively high, the resin may gel.

The average polymerization degree of the PVA-based resin may beappropriately selected in accordance with purposes. The averagepolymerization degree is typically from 1,000 to 10,000, preferably from1,200 to 4,500, more preferably from 1,500 to 4,300. The averagepolymerization degree may be determined in conformity with JIS K6726-1994.

The polarizer (except the non-polarization portions) preferably showsabsorption dichroism at any wavelength in the wavelength range of from380 nm to 780 nm. The single axis transmittance (Ts) of the polarizer(except the non-polarization portions) is preferably 39% or more, morepreferably 39.5% or more, still more preferably 40% or more,particularly preferably 40.5% or more. A theoretical upper limit for thesingle axis transmittance is 50%, and a practical upper limit thereforis 46%. In addition, the single axis transmittance (Ts) is a Y valuemeasured with the two-degree field of view (C light source) of JIS Z8701 and subjected to visibility correction, and may be measured with,for example, a microspectroscopic system (manufactured by Lambda VisionInc., LVmicro). The polarization degree of the polarizer (except thenon-polarization portions) is preferably 99.9% or more, more preferably99.93% or more, still more preferably 99.95% or more.

The non-polarization portions are preferably decolored portions formedby decoloring of the polarizer. The transmittance of each of thenon-polarization portions (e.g., a transmittance measured with lighthaving a wavelength of 550 nm at 23° C.) is preferably 50% or more, morepreferably 60% or more, still more preferably 75% or more, particularlypreferably 90% or more. With such transmittance, desired transparency asa non-polarization portion can be secured. As a result, when thepolarizer is arranged so that the non-polarization portions may eachcorrespond to the camera portion of an image display apparatus, anadverse effect on the photographing performance of its camera can beprevented.

The non-polarization portions are preferably low concentration portionseach having a relatively low content of the dichromatic substance.Specifically, the portions are low concentration portions each having acontent of the dichromatic substance lower than that of any otherportion. According to such construction, a problem in terms of quality,such as cracking, delamination (interlayer peeling), or adhesiveprotrusion, is avoided as compared to the case where thenon-polarization portions are formed mechanically (e.g., by a methodinvolving mechanically punching out the portions through the use ofchisel punching, a plotter, a water jet, or the like). In addition, thecontent of the dichromatic substance itself in each of the lowconcentration portions is low, and hence the transparency of each of thenon-polarization portions is satisfactorily maintained as compared tothe case where the non-polarization portions are formed by decomposingthe dichromatic substance with laser light or the like.

The low concentration portions are portions each having a content of thedichromatic substance lower than that of the other portion. The contentof the dichromatic substance in each of the low concentration portionsis preferably 1.0 wt % or less, more preferably 0.5 wt % or less, stillmore preferably 0.2 wt % or less. When the content of the dichromaticsubstance in each of the low concentration portions falls within suchrange, desired transparency can be sufficiently imparted to each of thelow concentration portions. When each of the low concentration portionsis caused to correspond to, for example, the camera portion of an imagedisplay apparatus, photographing performance that is extremely excellentfrom both the viewpoints of brightness and color tones can be realized.Meanwhile, a lower limit for the content of the dichromatic substance ineach of the low concentration portions is typically equal to or lessthan a detection limit. When iodine is used as the dichromaticsubstance, the iodine content is determined from, for example, acalibration curve produced in advance from an X-ray intensity measuredby X-ray fluorescence analysis through the use of a standard sample.

A difference between the content of the dichromatic substance in theother portion and the content of the dichromatic substance in each ofthe low concentration portions is preferably 0.5 wt % or more, morepreferably 1 wt % or more. When the difference between the contentsfalls within such range, low concentration portions each having desiredtransparency can be formed.

The content of an alkali metal and/or an alkaline earth metal in each ofthe low concentration portions is preferably 3.6 wt % or less, morepreferably 2.5 wt % or less, still more preferably 1.0 wt % or less,particularly preferably 0.5 wt % or less. When the content of the alkalimetal and/or the alkaline earth metal in each of the low concentrationportions falls within such range, the shapes of the low concentrationportions formed by contact with a basic solution to be described latercan be satisfactorily maintained (i.e., low concentration portions eachhaving excellent dimensional stability can be achieved). The content canbe determined from, for example, a calibration curve produced in advancefrom an X-ray intensity measured by X-ray fluorescence analysis throughthe use of a standard sample. Such content can be achieved by reducingthe amount of the alkali metal and/or the alkaline earth metal in acontact portion in the contact with the basic solution to be describedlater.

The thickness of the polarizer may be set to any appropriate value. Thethickness is preferably 30 μm or less, more preferably 25 μm or less,still more preferably 20 μm or less, particularly preferably 10 μm orless. Meanwhile, the thickness is preferably 0.5 μm or more, morepreferably 1 μm or more. With such thickness, a polarizer havingexcellent durability and excellent optical characteristics can beobtained. As the thickness of the polarizer becomes smaller, thenon-polarization portions can be formed more satisfactorily. Forexample, when the non-polarization portions are formed by decoloringbased on a chemical treatment, the time period for which a decoloringliquid and the resin film (polarizer) are brought into contact with eachother can be shortened. Specifically, non-polarization portions eachhaving a higher transmittance can be formed in a shorter time period.

The thickness of a portion with which the decoloring liquid (e.g., abasic solution) has been brought into contact can be smaller than thatof any other portion. The tendency can be strengthened by increasing thetransmittance of each of the non-polarization portions to be obtained bythe decoloring. When the thickness of the resin film is reduced, a stepdifference between each of the non-polarization portions and any otherportion can be reduced while the high transmittance (preferably 90% ormore) of each of the non-polarization portions is achieved. Thus, aninconvenience that may be caused by the step difference can beprevented. Possible examples of the inconvenience include the followinginconveniences: when the long polarizer is wound in a roll shape, thestep difference between each of the non-polarization portions and anyother portion is transferred as a winding trace onto a portion where apart of the polarizer is superimposed on another part thereof; airbubbles occur owing to the step difference between each of thenon-polarization portions and any other portion at the time of thebonding of the polarizer to any other constituent member, such as aprotective film; and the step difference is visually recognized in afinal product. The prevention of any such inconvenience may be capableof contributing to the suppression of a variation in quality betweenpolarizers to be finally used, the polarizers being obtained by cuttingthe polarizer of the present invention. It is assumed that such effectcan be significant, for example, when the transmittance of each of thenon-polarization portions is 90% or more and/or when the content of thedichromatic substance in each of the portions is 0.2 wt % or less. Thefact that the transmittance of each of the non-polarization portions isas high as 90% or more can also contribute to the suppression of thevariation in quality between the polarizers to be finally used.Specifically, in the case where the non-polarization portions are formedby the contact of the decoloring liquid, when a decoloring degree isinsufficient, a variation in transmittance between the non-polarizationportions to be obtained is liable to occur. However, the decoloredstates of the non-polarization portions can be stably controlled bysetting the transmittance to 90% or more and/or by setting the contentof the dichromatic substance to 0.2 wt % or less (by strengthening thedecoloring degree).

In one embodiment, the non-polarization portions are thin portionsthinner than any other portion. For example, the thin portions are eachobtained by forming a recessed portion having a recessed surface on onesurface side of the polarizer. In this case, the step difference betweeneach of the non-polarization portions and any other portion (depth ofthe recessed portion) is, for example, 0.02 μm or more. Meanwhile, thestep difference is preferably 2 μm or less, more preferably 1 μm orless. When the non-polarization portions are formed by decoloring to bedescribed later (e.g., when the transmittance of each of thenon-polarization portions is 90% or more and/or when the content of thedichromatic substance in each of the portions is 0.2 wt % or less), suchstep difference is formed in some cases. However, when an upper limitfor the step difference falls within such range, an inconvenience due tothe step difference, such as a winding trace due to roll forming, may besatisfactorily suppressed. As a result, the variation in quality betweenthe polarizers to be finally used, the polarizers being obtained bycutting the polarizer of the present invention, can be significantlysuppressed. The term “step difference (depth of the recessed portion)”as used herein refers to the depth of the deepest portion of therecessed portion.

The recessed portion having a recessed surface on one surface side isformed by, for example, causing a decoloring liquid to act only from onesurface side of the polarizer. When the depth of the recessed portion tobe formed after the decoloring treatment is set within theabove-mentioned range, a treatment after the decoloring to be describedlater can be uniformly performed. In addition, when the recessed portioncan be formed only on the one surface side, it is assumed that theoccurrence of an inconvenience due to the step difference, such as awinding trace due to roll forming, is prevented, and hence the variationin quality between the polarizers to be finally used can be suppressed.

The absorption axis of the polarizer may be set to any appropriatedirection in accordance with purposes. The direction of the absorptionaxis may be, for example, the lengthwise direction or the widthwisedirection. A polarizer having an absorption axis in its lengthwisedirection has an advantage in that the polarizer is excellent inproduction efficiency. A polarizer having an absorption axis in itswidthwise direction has an advantage in that the polarizer can belaminated together with, for example, a retardation film having a slowaxis in its lengthwise direction by a so-called roll-to-roll process.The term “roll-to-roll process” as used herein means that roll-shapedfilms are bonded to each other with their lengthwise directions alignedwith each other while being conveyed.

A resin film (typically a PVA-based resin film) constituting thepolarizer may be a single film, or may be a resin layer (typically aPVA-based resin layer) formed on a resin substrate. The PVA-based resinlayer may be formed by applying an application liquid containing aPVA-based resin onto the resin substrate, or may be formed by laminatingthe PVA-based resin film onto the resin substrate. The case where thepolarizer is the PVA-based resin layer formed on the resin substrate isspecifically described below. Here, the case where the PVA-based resinlayer is formed by application is described, but the same holds true forthe case where the PVA-based resin film is laminated. In the case wherethe polarizer is a single PVA-based resin film, the polarizer may beproduced by a method well-known and commonly used in the art, and hencedetailed description of the case is omitted.

A-1-1. Production of Laminate

Initially, a laminate of the resin substrate and the PVA-based resinlayer is produced by applying the application liquid containing thePVA-based resin onto the resin substrate, and drying the liquid to formthe PVA-based resin layer.

Any appropriate thermoplastic resin may be adopted as a formationmaterial for the resin substrate. Examples of the thermoplastic resininclude: an ester-based resin, such as a polyethyleneterephthalate-based resin; a cycloolefin-based resin, such as anorbornene-based resin; an olefin-based resin, such as polypropylene; apolyamide-based resin; a polycarbonate-based resin; and copolymer resinsthereof. Of those, a norbornene-based resin and an amorphouspolyethylene terephthalate-based resin are preferred.

In one embodiment, an amorphous (uncrystallized) polyethyleneterephthalate-based resin is preferably used. In particular, anon-crystalline (hardly crystallizable) polyethylene terephthalate-basedresin is preferably used. Specific examples of the non-crystallinepolyethylene terephthalate-based resin include: a copolymer furthercontaining isophthalic acid as a dicarboxylic acid; and a copolymerfurther containing cyclohexanedimethanol as a glycol.

When an underwater stretching mode is adopted in stretching to bedescribed later, the resin substrate absorbs water and the water canfunction like a plasticizer to plasticize the substrate. As a result, astretching stress can be significantly reduced and hence the laminatecan be stretched at a high ratio. Accordingly, stretchability moreexcellent than that at the time of in-air stretching can be achieved. Asa result, a polarizer having excellent optical characteristics can beproduced. In one embodiment, the water absorption ratio of the resinsubstrate is preferably 0.2% or more, more preferably 0.3% or more.Meanwhile, the water absorption ratio of the resin substrate ispreferably 3.0% or less, more preferably 1.0% or less. The use of suchresin substrate can prevent an inconvenience, such as the deteriorationof the external appearance of the polarizer to be obtained due to aremarkable reduction in dimensional stability at the time of theproduction. In addition, the use can prevent the rupture of thesubstrate at the time of underwater stretching and the peeling of thePVA-based resin layer from the resin substrate. The water absorptionratio of the resin substrate may be adjusted by, for example,introducing a modification group into the formation material. The waterabsorption ratio is a value determined in conformity with JIS K 7209.

The glass transition temperature (Tg) of the resin substrate ispreferably 170° C. or less. The use of such resin substrate cansufficiently secure the stretchability of the laminate while suppressingthe crystallization of the PVA-based resin layer. Further, inconsideration of the plasticization of the resin substrate by water andsatisfactory performance of the underwater stretching, the glasstransition temperature is more preferably 120° C. or less. In oneembodiment, the glass transition temperature of the resin substrate ispreferably 60° C. or more. The use of such resin substrate prevents aninconvenience, such as the deformation (e.g., the occurrence ofunevenness, a sag, or a wrinkle) of the resin substrate at the time ofthe application and drying of the application liquid containing thePVA-based resin, and hence enables satisfactory production of thelaminate. In addition, the use enables satisfactory performance of thestretching of the PVA-based resin layer at a suitable temperature (e.g.,about 60° C.). In another embodiment, the glass transition temperaturemay be lower than 60° C. as long as the resin substrate does not deformat the time of the application and drying of the application liquidcontaining the PVA-based resin. The glass transition temperature of theresin substrate may be adjusted by, for example, introducing amodification group into the formation material or incorporating acrystallized material into the formation material and heating thematerial. The glass transition temperature (Tg) is a value determined inconformity with JIS K 7121.

The thickness of the resin substrate before the stretching is preferablyfrom 20 μm to 300 μm, more preferably from 50 μm to 200 μm. When thethickness is less than 20 μm, it may become difficult to form thePVA-based resin layer. When the thickness is more than 300 μm, there isa risk in that, for example, in the underwater stretching, a long timeperiod is required for the resin substrate to absorb water, and anexcessively large load is required for the stretching.

The PVA-based resin forming the PVA-based resin layer is as described inthe section A-1.

The application liquid is typically a solution in which the PVA-basedresin is dissolved in a solvent. Examples of the solvent include water,dimethyl sulfoxide, dimethylformamide, dimethylacetamide,N-methylpyrrolidone, various glycols, polyhydric alcohols, such astrimethylolpropane, and amines, such as ethylenediamine anddiethylenetriamine. Those solvents may be used alone or in combination.Of those, water is preferred. The PVA-based resin concentration of thesolution is preferably from 3 parts by weight to 20 parts by weight withrespect to 100 parts by weight of the solvent. Such resin concentrationenables the formation of a uniform applied film closely adhering to theresin substrate.

The application liquid may be compounded with an additive. Examples ofthe additive include a plasticizer and a surfactant. Examples of theplasticizer include polyhydric alcohols, such as ethylene glycol andglycerin. The surfactant is, for example, a nonionic surfactant. Anysuch additive may be used for the purpose of further improving theuniformity, dyeability, and stretchability of the PVA-based resin layerto be obtained.

Any appropriate method may be adopted as a method of applying theapplication liquid. Examples thereof include a roll coating method, aspin coating method, a wire bar coating method, a dip coating method, adie coating method, a curtain coating method, a spray coating method,and a knife coating method (such as a comma coating method).

The temperature at which the application liquid is applied and dried ispreferably 50° C. or more.

The thickness of the PVA-based resin layer before the stretching ispreferably from 3 μm to 40 μm, more preferably from 3 μm to 20 μm.

Before the formation of the PVA-based resin layer, the resin substratemay be subjected to a surface treatment (e.g., a corona treatment), oran easy-adhesion layer may be formed on the resin substrate. Theperformance of any such treatment can improve adhesiveness between theresin substrate and the PVA-based resin layer.

A-1-2. Stretching of Laminate

Any appropriate method may be adopted as a method of stretching thelaminate. Specifically, fixed-end stretching may be adopted, or free-endstretching (e.g., a method involving passing the laminate between rollshaving different peripheral speeds to uniaxially stretch the laminate)may be adopted. Of those, free-end stretching is preferred.

The stretching direction of the laminate may be appropriately set. Inone embodiment, the stretching is performed in the lengthwise directionof a long laminate. As a result, the absorption axis of the polarizer tobe obtained can be expressed in the lengthwise direction. In this case,the method involving passing the laminate between the rolls havingdifferent peripheral speeds to stretch the laminate is typicallyadopted. In another embodiment, the stretching is performed in thewidthwise direction of the long laminate. As a result, the absorptionaxis of the polarizer to be obtained can be expressed in the widthwisedirection. In this case, a method involving stretching the laminate witha tenter stretching machine is typically adopted.

A stretching mode is not particularly limited, and may be an in-airstretching mode, or may be an underwater stretching mode. Of those, anunderwater stretching mode is preferred. According to the underwaterstretching mode, the stretching can be performed at a temperature lowerthan the glass transition temperature (typically about 80° C.) of theresin substrate or the PVA-based resin layer, and hence the PVA-basedresin layer can be stretched at a high ratio while its crystallizationis suppressed. As a result, a polarizer having excellent opticalcharacteristics can be produced.

The stretching of the laminate may be performed in one stage, or may beperformed in a plurality of stages. When the stretching is performed ina plurality of stages, for example, the free-end stretching and thefixed-end stretching may be combined, or the underwater stretching modeand the in-air stretching mode may be combined. In addition, when thestretching is performed in the plurality of stages, the stretching ratio(maximum stretching ratio) of the laminate to be described later is theproduct of stretching ratios at the respective stages.

The stretching temperature of the laminate may be set to any appropriatevalue in accordance with, for example, the formation material for theresin substrate and the stretching mode. When the in-air stretching modeis adopted, the stretching temperature is preferably equal to or morethan the glass transition temperature (Tg) of the resin substrate, morepreferably equal to or more than Tg+10° C., particularly preferablyequal to or more than Tg+15° C. Meanwhile, the stretching temperature ofthe laminate is preferably 170° C. or less. When the stretching isperformed at such temperature, rapid progress of the crystallization ofthe PVA-based resin is suppressed, and hence an inconvenience due to thecrystallization (e.g., the inhibition of the orientation of thePVA-based resin layer by the stretching) can be suppressed.

When the underwater stretching mode is adopted, the liquid temperatureof a stretching bath is preferably from 40° C. to 85° C., morepreferably from 50° C. to 85° C. At such temperature, the stretching canbe performed at a high ratio while the dissolution of the PVA-basedresin layer is suppressed. Specifically, as described above, the glasstransition temperature (Tg) of the resin substrate is preferably 60° C.or more in relation to the formation of the PVA-based resin layer. Inthis case, when the stretching temperature is less than 40° C., there isa risk in that the stretching cannot be satisfactorily performed even inconsideration of the plasticization of the resin substrate by water.Meanwhile, as the temperature of the stretching bath increases, there isa risk in that the solubility of the PVA-based resin layer is raised andhence excellent optical characteristics cannot be obtained. The timeperiod for which the laminate is immersed in the stretching bath ispreferably from 15 seconds to 5 minutes.

When the underwater stretching mode is adopted, the laminate ispreferably stretched while being immersed in an aqueous solution ofboric acid (boric acid underwater stretching). The use of the aqueoussolution of boric acid as the stretching bath can impart, to thePVA-based resin layer, rigidity enabling the layer to withstand atension to be applied at the time of the stretching and water resistancepreventing the layer from dissolving in water. Specifically, boric acidcan produce a tetrahydroxyboric acid anion in the aqueous solution tocross-link with the PVA-based resin through a hydrogen bond. As aresult, the rigidity and the water resistance are imparted to thePVA-based resin layer, and hence the layer can be satisfactorilystretched. Accordingly, a polarizer having excellent opticalcharacteristics can be produced.

The aqueous solution of boric acid is preferably obtained by dissolvingboric acid and/or a borate in water serving as a solvent. Theconcentration of boric acid is preferably from 1 part by weight to 10parts by weight with respect to 100 parts by weight of water. Thesetting of the boric acid concentration to 1 part by weight or more caneffectively suppress the dissolution of the PVA-based resin layer, andhence enables the production of a polarizer having highercharacteristics. In addition to boric acid or the borate, an aqueoussolution obtained by dissolving, for example, a boron compound, such asborax, and glyoxal or glutaraldehyde in a solvent may also be used.

When the PVA-based resin layer is caused to adsorb a dichromaticsubstance (typically iodine) by dyeing to be described later in advance,the stretching bath (aqueous solution of boric acid) is preferablycompounded with an iodide. The compounding of the bath with the iodidecan suppress the elution of iodine that the PVA-based resin layer hasbeen caused to adsorb. Examples of the iodide include potassium iodide,lithium iodide, sodium iodide, zinc iodide, aluminum iodide, leadiodide, copper iodide, barium iodide, calcium iodide, tin iodide, andtitanium iodide. Of those, potassium iodide is preferred. Theconcentration of the iodide is preferably from 0.05 part by weight to 15parts by weight, more preferably from 0.5 part by weight to 8 parts byweight with respect to 100 parts by weight of water.

The stretching ratio (maximum stretching ratio) of the laminate ispreferably 5.0 times or more with respect to the original length of thelaminate. Such high stretching ratio can be achieved by adopting, forexample, the underwater stretching mode (boric acid underwaterstretching). The term “maximum stretching ratio” as used herein refersto a stretching ratio immediately before the rupture of the laminate,and refers to a value lower than a separately determined value for thestretching ratio at which the laminate is ruptured by 0.2.

In a preferred embodiment, after the laminate has been subjected toin-air stretching at a high temperature (of, for example, 95° C. ormore), the boric acid underwater stretching and the dyeing to bedescribed later are performed. Such in-air stretching is hereinafterreferred to as “in-air auxiliary stretching” because the stretching maybe regarded as stretching preliminary or auxiliary to the boric acidunderwater stretching.

When the in-air auxiliary stretching is combined with the boric acidunderwater stretching, the laminate can be stretched at a higher ratioin some cases. As a result, a polarizer having more excellent opticalcharacteristics (e.g., a polarization degree) can be produced. Forexample, when a polyethylene terephthalate-based resin is used as theresin substrate, in the case where the in-air auxiliary stretching andthe boric acid underwater stretching are combined, the laminate can bestretched, while the orientation of the resin substrate is suppressed,to a large extent as compared to the case where the stretching isperformed only by the boric acid underwater stretching. As theorientation property of the resin substrate is improved, a stretchingtension increases, and hence it becomes difficult to stably stretch thelaminate or the laminate is ruptured. Accordingly, when the laminate isstretched while the orientation of the resin substrate is suppressed,the laminate can be stretched at a higher ratio.

In addition, when the in-air auxiliary stretching is combined with theboric acid underwater stretching, the orientation property of thePVA-based resin is improved, and hence the orientation property of thePVA-based resin can be improved even after the boric acid underwaterstretching. Specifically, the following assumption is made: when theorientation property of the PVA-based resin is improved by the in-airauxiliary stretching in advance, the PVA-based resin easily cross-linkswith boric acid at the time of the boric acid underwater stretching, andthe laminate is stretched under a state in which boric acid serves as anode, and hence the orientation property of the PVA-based resin isimproved even after the boric acid underwater stretching. As a result, apolarizer having excellent optical characteristics (e.g., a polarizationdegree) can be produced.

The stretching ratio of the laminate in the in-air auxiliary stretchingis preferably 3.5 times or less. The stretching temperate in the in-airauxiliary stretching is preferably equal to or more than the glasstransition temperature of the PVA-based resin. The stretchingtemperature is preferably from 95° C. to 150° C. The maximum stretchingratio of the laminate when the in-air auxiliary stretching and the boricacid underwater stretching are combined is preferably 5.0 times or more,more preferably 5.5 times or more, still more preferably 6.0 times ormore with respect to the original length of the laminate.

A-1-3. Dyeing

The dyeing is typically performed by causing the PVA-based resin layerto adsorb the dichromatic substance (preferably iodine). A method forthe adsorption is, for example, a method involving immersing thePVA-based resin layer (laminate) in a dyeing liquid containing iodine, amethod involving applying the dyeing liquid to the PVA-based resinlayer, or a method involving spraying the dyeing liquid on the PVA-basedresin layer. Of those, a method involving immersing the laminate in thedyeing liquid is preferred. This is because iodine can satisfactorilyadsorb to the laminate.

The dyeing liquid is preferably an aqueous solution of iodine. Thecompounding amount of iodine is preferably from 0.1 part by weight to0.5 part by weight with respect to 100 parts by weight of water. Inorder that the solubility of iodine in water may be increased, theaqueous solution of iodine is preferably compounded with an iodide.Specific examples of the iodide are as described above. The compoundingamount of the iodide is preferably from 0.02 part by weight to 20 partsby weight, more preferably from 0.1 part by weight to 10 parts by weightwith respect to 100 parts by weight of water. The liquid temperature ofthe dyeing liquid at the time of the dyeing is preferably from 20° C. to50° C. in order that the dissolution of the PVA-based resin may besuppressed. When the PVA-based resin layer is immersed in the dyeingliquid, an immersion time is preferably from 5 seconds to 5 minutes inorder that the transmittance of the PVA-based resin layer may besecured. In addition, the dyeing conditions (the concentrations, theliquid temperature, and the immersion time) may be set so that thepolarization degree or single axis transmittance of the polarizer to befinally obtained may fall within a predetermined range. In oneembodiment, the immersion time is set so that the polarization degree ofthe polarizer to be obtained may be 99.98% or more. In anotherembodiment, the immersion time is set so that the single axistransmittance of the polarizer to be obtained may be from 40% to 44%.

A dyeing treatment may be performed at any appropriate timing. When theunderwater stretching is performed, the treatment is preferablyperformed before the underwater stretching.

A-1-4. Other Treatments

The laminate may be appropriately subjected to a treatment for turningits PVA-based resin layer into a polarizer in addition to the stretchingand the dyeing. Examples of the treatment for turning the layer into thepolarizer include an insolubilizing treatment, a cross-linkingtreatment, a washing treatment, and a drying treatment. The number oftimes of each of those treatments, the order in which the treatments areperformed, and the like are not particularly limited.

The insolubilizing treatment is typically performed by immersing thePVA-based resin layer in an aqueous solution of boric acid. Theperformance of the insolubilizing treatment can impart water resistanceto the PVA-based resin layer. The concentration of boric acid in theaqueous solution is preferably from 1 part by weight to 4 parts byweight with respect to 100 parts by weight of water. The liquidtemperature of the insolubilizing bath (aqueous solution of boric acid)is preferably from 20° C. to 50° C. The insolubilizing treatment ispreferably performed before the underwater stretching and the dyeingtreatment.

The cross-linking treatment is typically performed by immersing thePVA-based resin layer in an aqueous solution of boric acid. Theperformance of the cross-linking treatment can impart water resistanceto the PVA-based resin layer. The concentration of boric acid in theaqueous solution is preferably from 1 part by weight to 5 parts byweight with respect to 100 parts by weight of water. In addition, whenthe cross-linking treatment is performed after the dyeing treatment, thesolution is preferably further compounded with an iodide. Thecompounding of the solution with the iodide can suppress the elution ofiodine that the PVA-based resin layer has been caused to adsorb. Thecompounding amount of the iodide is preferably from 1 part by weight to5 parts by weight with respect to 100 parts by weight of water. Specificexamples of the iodide are as described above. The liquid temperature ofthe cross-linking bath (aqueous solution of boric acid) is preferablyfrom 20° C. to 60° C. The cross-linking treatment is preferablyperformed before the underwater stretching. In a preferred embodiment,the dyeing treatment, the cross-linking treatment, and the underwaterstretching are performed in the stated order.

The washing treatment is typically performed by immersing the PVA-basedresin layer in an aqueous solution of potassium iodide. A dryingtemperature in the drying treatment is preferably from 30° C. to 100° C.

A-2. Surface Protective Film

The surface protective film 20 has the through-holes 21, 21, . . .arranged according to the predetermined pattern. The positions at whichthe through-holes are arranged correspond to the positions at which theexposed portions (the non-polarization portions) are formed. Thearrangement pattern of the through-holes illustrated in FIG. 4corresponds to the arrangement pattern of the exposed portions (thenon-polarization portions) illustrated in FIG. 3A. The through-holes mayeach have any appropriate shape. The shapes of the through-holescorrespond to the plan-view shapes of the non-polarization portions tobe formed. The through-holes may each be formed by, for example,mechanical punching (e.g., punching, chisel punching, a plotter, or awater jet) or the removal of a predetermined portion of the film (e.g.,laser ablation or chemical dissolution).

The surface protective film is preferably a film having a high hardness(e.g., a modulus of elasticity). This is because the deformation of thethrough-holes at the time of the conveyance and/or the lamination can beprevented. As materials for forming the first surface protective film,there are given, for example: an ester-based resin, such as apolyethylene terephthalate-based resin; a cycloolefin-based resin, suchas a norbornene-based resin; an olefin-based resin, such aspolypropylene; a polyamide-based resin; a polycarbonate-based resin; andcopolymer resins thereof. Of those, an ester-based resin (especially apolyethylene terephthalate-based resin) is preferred. Such material hasan advantage in that its modulus of elasticity is sufficiently high, andhence the deformation of the through-holes hardly occurs even when atension is applied at the time of the conveyance and/or the lamination.

The thickness of the surface protective film is typically from 20 μm to250 μm, preferably from 30 μm to 150 μm. Such thickness has an advantagein that the deformation of the through-holes hardly occurs even when atension is applied at the time of the conveyance and/or the bonding.

The modulus of elasticity of the surface protective film is preferablyfrom 2.2 kN/mm² to 4.8 kN/mm². When the modulus of elasticity of thefirst surface protective film falls within such range, the followingadvantage is obtained: the deformation of the through-holes hardlyoccurs even when a tension is applied at the time of the conveyanceand/or the lamination. The modulus of elasticity is measured inconformity with JIS K 6781.

The tensile elongation of the surface protective film is preferably from90% to 170%. When the tensile elongation of the first surface protectivefilm falls within such range, the following advantage is obtained: thefilm is hardly ruptured during the conveyance. The tensile elongation ismeasured in conformity with JIS K 6781.

In one embodiment, as illustrated in FIG. 4, the surface protective film20 that is long and has the through-holes 21, 21, . . . arrangedaccording to a predetermined pattern is laminated on the long polarizer10 by the roll-to-roll process. The use of the surface protective filmhaving the through-holes enables satisfactory formation of the exposedportions (non-polarization portions) of the polarizer.

When the polarizer and the surface protective film are laminated by theroll-to-roll process, the following may be performed: the long surfaceprotective film is unwound from a surface protective film roll in whichthe surface protective film has been wound in a roll shape, and islaminated on the polarizer. The following may also be performed: afterthe through-holes have been formed in the surface protective film, thesurface protective film is continuously laminated on the polarizer(without winding the surface protective film).

As described above, the surface protective film 20 is typically bondedto the polarizer 10 through intermediation of any appropriatepressure-sensitive adhesive in a peelable manner. It is preferred thatthe through-holes be formed in the surface protective film on which apressure-sensitive adhesive layer has been formed in advance, and theresultant be bonded to the polarizer. A pressure-sensitive adhesive tobe used in the lamination of the surface protective film is, forexample, a pressure-sensitive adhesive composition obtained by using anacrylic resin, a styrene-based resin, a silicone-based resin, or thelike as a base resin, and compounding the base resin with across-linking agent selected from an isocyanate compound, an epoxycompound, an aziridine compound, and the like, and with a silanecoupling agent or the like. The thickness of the pressure-sensitiveadhesive layer is typically from 1 μm to 60 μm, preferably from 3 μm to30 μm. When the pressure-sensitive adhesive layer is excessively thin,an inconvenience, such as a reduction in pressure-sensitive adhesiveproperty or the facilitation of the inclusion of air bubbles, may occur,and when the layer is excessively thick, an inconvenience, such as theprotrusion of the pressure-sensitive adhesive, may occur. An acrylicpressure-sensitive adhesive is preferably used from the viewpoints of,for example, chemical resistance, adhesiveness (for, for example,preventing the penetration of a solution at the time of immersion to bedescribed later), and a degree of freedom to an adherend.

A-3. Others

As materials for forming the protective film 30, there are given, forexample, a cellulose-based resin, such as diacetyl cellulose ortriacetyl cellulose, a (meth)acrylic resin, a cycloolefin-based resin,an olefin-based resin, such as polypropylene, an ester-based resin, suchas a polyethylene terephthalate-based resin, a polyamide-based resin, apolycarbonate-based resin, and copolymer resins thereof. The thicknessof the protective film is typically from 10 μm to 100 μm. In oneembodiment, the thickness of the protective film is 80 μm or less. Theuse of a protective film having such thickness can contribute to thethinning of a polarizing plate to be obtained. Meanwhile, when a longpolarizing plate obtained by arranging a protective film having suchthickness on the other surface side of the polarizer having the recessedportions formed on the one surface side is wound in a roll shape, aninconvenience due to the step difference, such as the transfer of therecessed portions as winding traces onto the protective film, may beliable to occur. In such embodiment, a merit of reducing the depths ofthe recessed portions can be significantly obtained.

The protective film may have an optical compensation function (i.e., thefilm may have an appropriate refractive index ellipsoid, an appropriatein-plane retardation, and an appropriate thickness direction retardationthat are in accordance with purposes). The protective film is typicallylaminated on the polarizer through intermediation of an adhesion layer(specifically an adhesive layer or a pressure-sensitive adhesive layer).The adhesive layer is typically formed of a PVA-based adhesive or anactive energy ray-curable adhesive. The pressure-sensitive adhesivelayer is typically formed of an acrylic pressure-sensitive adhesive.

When the polarizer 10 is a resin layer formed on a resin substrate, thelamination of the protective film 30 and/or the peeling of the resinsubstrate may be performed. In one embodiment, the protective film islaminated on the polarizer surface of a laminate of the resin substrateand the polarizer by the roll-to-roll process, and then the resinsubstrate is peeled.

The same film as the first surface protective film except that nothrough-holes are arranged may be used as the second surface protectivefilm 40. Further, a soft (e.g., low-modulus of elasticity) film like apolyolefin (e.g., polyethylene) film may also be used as the secondsurface protective film. In one embodiment, the second surfaceprotective film 40 is laminated on one side of the polarizer 10 by theroll-to-roll process. Specifically, the second surface protective film40 is bonded to the polarizer 10 or the protective film 30 throughintermediation of any appropriate pressure-sensitive adhesive in apeelable manner. The use of the second surface protective film enablesappropriate protection of the polarizer or the polarizing plate(polarizer/protective film) in a chemical treatment to be describedlater. The second surface protective film may be laminated on thepolarizer or the polarizing plate simultaneously with the first surfaceprotective film, may be laminated before the lamination of the firstsurface protective film, or may be laminated after the lamination of thefirst surface protective film. The second surface protective film ispreferably laminated before the lamination of the first surfaceprotective film on the polarizer or the polarizing plate. Such procedurehas the following advantages: the protective film is prevented frombeing flawed; and the through-holes formed in the first surfaceprotective film are prevented from being transferred as traces onto theprotective film at the time of its winding. When the second surfaceprotective film is laminated before the lamination of the first surfaceprotective film, for example, the following may be performed. A laminateof the protective film and the second surface protective film isproduced, and the laminate is laminated on the laminate of the resinsubstrate and the polarizer. After that, the resin substrate is peeledand the first surface protective film is laminated on the peeledsurface.

The polarizing film laminate of the present invention may furtherinclude any appropriate optical functional layer in accordance withpurposes, though the layer is not shown. Typical examples of the opticalfunctional layer include a retardation film (optical compensation film)and a surface-treated layer.

B. Formation of Non-Polarization Portions

The non-polarization portions may be formed by any appropriate method aslong as the desired optical characteristics are obtained. In oneembodiment, the non-polarization portions are formed by decoloring thepolarizer through a chemical treatment. When the chemical treatment isperformed, in addition to the protection with the first surfaceprotective film, the other surface side of the polarizer 10 ispreferably protected with any appropriate film material. For example,the protective film 30 or the second surface protective film 40 is usedas the film material, and when the polarizer 10 is a resin layer formedon a resin substrate, the resin substrate is used.

The formation of the non-polarization portions is specifically describedbelow. The case where the non-polarization portions are formed in thepolarizer by decoloring based on a chemical treatment (hereinaftersometimes referred to as “chemical decoloring treatment”) in thepolarizing film laminate 100 of the illustrated example is described asa typical example. It is apparent to a person skilled in the art thatthe same procedure is applicable even to a construction different fromthe illustrated example.

The chemical decoloring treatment involves bringing the polarizing filmlaminate into contact with a basic solution. In the case where iodine isused as a dichromatic substance, when the basic solution is brought intocontact with a desired portion of the resin film, the iodine content ofthe contact portion can be easily reduced.

The contact between the laminate and the basic solution may be performedby any appropriate means. Typical examples thereof include: theimmersion of the laminate in the basic solution; and the application orspraying of the basic solution onto the laminate. Of those, immersion ispreferred. This is because of the following reason: the decoloringtreatment can be performed while the laminate is conveyed as illustratedin FIG. 5, and hence production efficiency is significantly high. Theuse of the first surface protective film (and, as required, the secondsurface protective film) enables the immersion. Specifically, when thelaminate is immersed in the basic solution, only portions in thepolarizer corresponding to the through-holes of the first surfaceprotective film are brought into contact with the basic solution. Forexample, in the case where the polarizer contains iodine as adichromatic substance, when the polarizer and the basic solution arebrought into contact with each other, the iodine concentrations of thecontact portions of the polarizer with the basic solution are reduced.As a result, the non-polarization portions can be selectively formedonly in the contact portions (that can be set by the through-holes ofthe first surface protective film). As described above, according tothis embodiment, the non-polarization portions can be selectively formedin the predetermined portions of the polarizer with extremely highproduction efficiency without any complicated operation. In the casewhere iodine remains in the polarizer, even when the non-polarizationportions are formed by breaking an iodine complex, there is a risk inthat the iodine complex is formed again in association with the use ofthe polarizer, and hence the non-polarization portions do not havedesired characteristics. In this embodiment, iodine itself is removedfrom the polarizer (substantially the non-polarization portions) by theremoval of the basic solution to be described later. As a result,changes in characteristics of the non-polarization portions inassociation with the use of the polarizer can be prevented.

The formation of the non-polarization portions with the basic solutionis described in more detail. After having been brought into contact witha predetermined portion of the polarizer, the basic solution permeatesinto the predetermined portion. The iodine complex in the predeterminedportion is reduced by a base in the basic solution to become an iodineion. The reduction of the iodine complex to the iodine ion substantiallyeliminates the polarization performance of the portion and hence leadsto the formation of a non-polarization portion in the portion. Inaddition, the reduction of the iodine complex increases thetransmittance of the portion. Iodine that has become the iodine ionmoves from the portion into the solvent of the basic solution. As aresult, through the removal of the basic solution to be described later,the iodine ion is also removed from the portion together with the basicsolution. Thus, a non-polarization portion (low concentration portion)is selectively formed in the predetermined portion of the polarizer, andthe non-polarization portion is a stable portion that does not changewith time. The permeation of the basic solution into even an undesiredportion (and as a result, the formation of a non-polarization portion inthe undesired portion) can be prevented by adjusting, for example, thematerial, thickness, and mechanical characteristics of the first surfaceprotective film, the concentration of the basic solution, and the timeperiod for which the polarizing film laminate is immersed in the basicsolution.

Any appropriate basic compound may be used as a basic compound in thebasic solution. Examples of the basic compound include: hydroxides ofalkali metals, such as sodium hydroxide, potassium hydroxide, andlithium hydroxide; hydroxides of alkaline earth metals, such as calciumhydroxide; inorganic alkali metal salts, such as sodium carbonate;organic alkali metal salts, such as sodium acetate; and ammonia water.Of those, hydroxides of alkali metals and/or alkaline earth metals arepreferably used, and sodium hydroxide, potassium hydroxide, and lithiumhydroxide are more preferably used. The use of such basic compound canefficiently ionize the iodine complex, and hence can form thenon-polarization portion with additional ease. Those basic compounds maybe used alone or in combination.

Any appropriate solvent may be used as the solvent of the basicsolution. Specific examples thereof include: water; alcohols, such asethanol and methanol; ethers; benzene; chloroform; and mixed solventsthereof. The solvent is preferably water or an alcohol because an iodineion satisfactorily migrates to the solvent and hence the iodine ion canbe easily removed in the subsequent removal of the basic solution.

The concentration of the basic solution is, for example, from 0.01 N to5 N, preferably from 0.05 N to 3 N, more preferably from 0.1 N to 2.5 N.When the concentration of the basic solution falls within such range, aniodine concentration in the polarizer can be efficiently reduced, andthe ionization of the iodine complex in a portion except a predeterminedportion can be prevented.

The liquid temperature of the basic solution is, for example, from 20°C. to 50° C. The time period for which the polarizing film laminate(substantially the predetermined portions of the polarizer) and thebasic solution are brought into contact with each other may be set inaccordance with the thickness of the polarizer, the kind of the basiccompound in the basic solution to be used, and the concentration of thebasic compound, and is, for example, from 5 seconds to 30 minutes.

Boric acid may be incorporated into the polarizer (resin film). Boricacid may be incorporated by bringing a boric acid solution (e.g., anaqueous solution of boric acid) into contact with the polarizer at thetime of, for example, the stretching treatment or the cross-linkingtreatment. The boric acid content of the polarizer (resin film) is, forexample, from 10 wt % to 30 wt %. In addition, a boric acid content in acontact portion with the basic solution is, for example, from 5 wt % to12 wt %.

After the contact with the basic solution, the amount of an alkali metaland/or an alkaline earth metal in the resin film is preferably reducedin the contact portion with which the basic solution has been broughtinto contact. The reduction of the amount of the alkali metal and/or thealkaline earth metal can provide a low concentration portion excellentin dimensional stability. Specifically, the shapes of the lowconcentration portions formed by the contact with the basic solution canbe maintained as they are even under a humidified environment.

When the basic solution is brought into contact with the resin film, ahydroxide of the alkali metal and/or the alkaline earth metal may remainin the contact portion. In addition, when the basic solution is broughtinto contact with the resin film, a metal salt of the alkali metaland/or the alkaline earth metal may be produced in the contact portion.The hydroxide or the metal salt may produce a hydroxide ion, and theproduced hydroxide ion may act on (decompose or reduce) a dichromaticsubstance (e.g., an iodine complex) present around the contact portionto expand a non-polarization region (low concentration region).Therefore, it is assumed that when the amount of the salt of the alkalimetal and/or the alkaline earth metal is reduced, the expansion of thenon-polarization region with time is suppressed and hence desired shapesof the non-polarization portions can be maintained.

The metal salt that may produce a hydroxide ion is, for example, aborate. The borate may be produced by the neutralization of boric acidin the resin film with a basic solution (a solution of a hydroxide of analkali metal and/or a hydroxide of an alkaline earth metal). Forexample, when the polarizer is placed under a humidified environment,the borate (metaborate) may be hydrolyzed to produce a hydroxide ion asrepresented by the following formulae.

In the formulae, X represents an alkali metal or an alkaline earthmetal.

The content of the alkali metal and/or the alkaline earth metal in thecontact portion is preferably reduced so that the content may be 3.6 wt% or less, preferably 2.5 wt % or less, more preferably 1.0 wt % orless, still more preferably 0.5 wt % or less.

The alkali metal and/or the alkaline earth metal may be incorporatedinto the resin film in advance by subjecting the film to varioustreatments for turning the film into a polarizer. Potassium may beincorporated into the resin film by bringing a solution of an iodide,such as potassium iodide, into contact with the film. The alkali metaland/or the alkaline earth metal to be typically incorporated into thepolarizer as described above may not adversely affect the dimensionalstability of each of the low concentration portions.

A method involving bringing a treatment liquid into contact with thecontact portion with the basic solution is preferably used as a methodfor the reduction. Such method can cause the alkali metal and/or thealkaline earth metal to migrate from the resin film to the treatmentliquid to reduce the content.

Any appropriate method may be adopted as a method for the contact of thetreatment liquid. Examples thereof include: a method involving dropping,applying, or spraying the treatment liquid onto the contact portion withthe basic solution; and a method involving immersing the contact portionwith the basic solution in the treatment liquid.

When the resin film is protected with any appropriate protectivematerial at the time of the contact with the basic solution, thetreatment liquid is preferably brought into contact with the film as itis (particularly in the case where the temperature of the treatmentliquid is 50° C. or more). Such mode can prevent reductions inpolarization characteristics due to the treatment liquid in a portionexcept the contact portion with the basic solution.

The treatment liquid may contain any appropriate solvent. Examples ofthe solvent include: water; alcohols, such as ethanol and methanol;ethers; benzene; chloroform; and mixed solvents thereof. Of those, wateror an alcohol is preferably used from the viewpoint that the alkalimetal and/or the alkaline earth metal are/is caused to efficientlymigrate. Any appropriate water may be used as water. Examples thereofinclude tap water, pure water, and deionized water.

The temperature of the treatment liquid at the time of the contact is,for example, 20° C. or more, preferably 50° C. or more, more preferably60° C. or more, still more preferably 70° C. or more. Such temperaturecan cause the alkali metal and/or the alkaline earth metal toefficiently migrate to the treatment liquid. Specifically, thetemperature can significantly increase the swelling ratio of the resinfilm to physically remove the alkali metal and/or the alkaline earthmetal in the resin film. Meanwhile, the temperature of water issubstantially 95° C. or less.

The time period for which the contact portion and the treatment liquidare brought into contact with each other may be appropriately adjustedin accordance with, for example, the method for the contact, thetemperature of the treatment liquid (water), and the thickness of theresin film. For example, when the contact portion is immersed in warmwater, the contact time is preferably from 10 seconds to 30 minutes,more preferably from 30 seconds to 15 minutes, still more preferablyfrom 60 seconds to 10 minutes.

In one embodiment, an acidic solution is used as the treatment liquid.The use of the acidic solution can neutralize the hydroxide of thealkali metal and/or the alkaline earth metal remaining in the resin filmto chemically remove the alkali metal and/or the alkaline earth metal inthe resin film.

Any appropriate acidic compound may be used as an acidic compound in theacidic solution. Examples of the acidic compound include: inorganicacids, such as hydrochloric acid, sulfuric acid, nitric acid, hydrogenfluoride, and boric acid; and organic acids, such as formic acid, oxalicacid, citric acid, acetic acid, and benzoic acid. Of those, an inorganicacid is preferred as the acidic compound in the acidic solution, andhydrochloric acid, sulfuric acid, or nitric acid is more preferred.Those acidic compounds may be used alone or in combination.

It is preferred that an acidic compound having an acidity stronger thanthat of boric acid be suitably used as the acidic compound. This isbecause the compound can act also on the metal salt (borate) of thealkali metal and/or the alkaline earth metal. Specifically, the alkalimetal and/or the alkaline earth metal in the resin film can bechemically removed by liberating boric acid from the borate.

An indicator of the acidity is, for example, an acid dissociationconstant (pKa), and an acidic compound having a pKa smaller than the pKa(9.2) of boric acid is preferably used. Specifically, the pKa ispreferably less than 9.2, more preferably 5 or less. The pKa may bemeasured with any appropriate measuring apparatus, and reference may bemade to a value disclosed in a literature, such as “Chemical HandbookFundamentals revised 5th edition” (edited by The Chemical Society ofJapan, Maruzen Publishing Co., Ltd.). In addition, in the case of anacidic compound that dissociates in a plurality of stages, its pKa valuemay change in each stage. When such acidic compound is used, such acompound that any one of the pKa values in the respective stages fallswithin the range is used. The pKa as used herein refers to a value in anaqueous solution at 25° C.

A difference between the pKa of the acidic compound and the pKa of boricacid is, for example, 2.0 or more, preferably from 2.5 to 15, morepreferably from 2.5 to 13. When the difference falls within such range,the alkali metal and/or the alkaline earth metal can be caused toefficiently migrate to the treatment liquid, and as a result, a desiredcontent of the alkali metal and/or the alkaline earth metal in each ofthe low concentration portions can be achieved.

Examples of the acidic compound that may satisfy the above-mentioned pKainclude: inorganic acids, such as hydrochloric acid (pKa: −3.7),sulfuric acid (pK₂: 1.96), nitric acid (pKa: −1.8), hydrogen fluoride(pKa: 3.17), and boric acid (pKa: 9.2); and organic acids, such asformic acid (pKa: 3.54), oxalic acid (pK₁: 1.04, pK₂: 3.82), citric acid(pK₁: 3.09, pK₂: 4.75, pK₃: 6.41), acetic acid (pKa: 4.8), and benzoicacid (pKa: 4.0).

The solvent of the acidic solution (treatment liquid) is as describedabove, and also in this embodiment in which the acidic solution is usedas the treatment liquid, the physical removal of the alkali metal and/orthe alkaline earth metal in the resin film may occur.

The concentration of the acidic solution is, for example, from 0.01 N to5 N, preferably from 0.05 N to 3 N, more preferably from 0.1 N to 2.5 N.

The liquid temperature of the acidic solution is, for example, from 20°C. to 50° C. The time period for which the resin film is brought intocontact with the acidic solution may be set in accordance with thethickness of the resin film, the kind of the acidic compound, and theconcentration of the acidic solution, and is, for example, from 5seconds to 30 minutes.

The resin film may be further subjected to any appropriate othertreatment in addition to the above-mentioned treatments. Examples of theother treatment include the removal of the basic solution and/or theacidic solution, and washing.

A method for the removal of the basic solution and/or the acidicsolution is specifically, for example, removal by wiping with a wastecloth or the like, removal by suction, natural drying, heat drying, blowdrying, or vacuum drying. The drying temperature is, for example, from20° C. to 100° C. The drying time is, for example, from 5 seconds to 600seconds.

The washing treatment is performed by any appropriate method. Examplesof a solution to be used in the washing treatment include pure water,alcohols, such as methanol and ethanol, an acidic aqueous solution, andmixed solvents thereof. The washing is typically performed while thelaminate is conveyed as illustrated in FIG. 5. The washing treatment maybe performed at any appropriate stage. The washing treatment may beperformed a plurality of times. In the illustrated example, after thecontact with the basic solution, washing with water, the contact withthe acidic solution, and washing with water are performed in the statedorder.

After the non-polarization portions have been formed as described above(preferably after the reduction of the amount of the alkali metal and/orthe alkaline earth metal), the first surface protective film and thesecond surface protective film may be typically peeled and removed.According to the polarizing film laminate of the present invention, thelamination of the polarizer and the surface protective film, thedecoloring, and the peeling of the surface protective film can beperformed while the laminate is conveyed in the lengthwise direction(i.e., continuously).

EXAMPLES

Now, the present invention is specifically described byway of Examples.However, the present invention is not limited to these Examples.

Example 1

An amorphous isophthalic acid-copolymerized polyethylene terephthalate(IPA-copolymerized PET) film of a long shape (thickness: 100 μm) havinga water absorption ratio of 0.75% and a Tg of 75° C. was used as a resinsubstrate. One surface of the substrate was subjected to a coronatreatment, and an aqueous solution containing polyvinyl alcohol(polymerization degree: 4,200, saponification degree: 99.2 mol %) andacetoacetyl-modified PVA (polymerization degree: 1,200, acetoacetylmodification degree: 4.6%, saponification degree: 99.0 mol % or more,manufactured by The Nippon Synthetic Chemical Industry Co., Ltd., tradename: “GOHSEFIMER Z-200”) ata ratio of 9:1 was applied to thecorona-treated surface and dried at 25° C. to form a PVA-based resinlayer having a thickness of 11 μm. Thus, a laminate was produced.

The resultant laminate was subjected to free-end uniaxial stretching inan oven at 120° C. between rolls having different peripheral speeds in alongitudinal direction (lengthwise direction) at 2.0 times (in-airauxiliary stretching).

Next, the laminate was immersed in an insolubilizing bath having aliquid temperature of 30° C. (an aqueous solution of boric acid obtainedby compounding 100 parts by weight of water with 4 parts by weight ofboric acid) for 30 seconds (insolubilizing treatment).

Next, the laminate was immersed in a dyeing bath having a liquidtemperature of 30° C. while an iodine concentration and an immersiontime were adjusted so that a polarizing plate to be obtained had apredetermined transmittance. In this example, the laminate was immersedin an aqueous solution of iodine, which was obtained by compounding 100parts by weight of water with 0.2 part by weight of iodine and 1.5 partsby weight of potassium iodide, for 60 seconds (dyeing treatment).

Next, the laminate was immersed in a cross-linking bath having a liquidtemperature of 30° C. (an aqueous solution of boric acid obtained bycompounding 100 parts by weight of water with 3 parts by weight ofpotassium iodide and 3 parts by weight of boric acid) for 30 seconds(cross-linking treatment).

After that, the laminate was subjected to uniaxial stretching betweenrolls having different peripheral speeds in a longitudinal direction(lengthwise direction) so that a total stretching ratio became 5.5 timeswhile being immersed in an aqueous solution of boric acid having aliquid temperature of 70° C. (an aqueous solution obtained bycompounding 100 parts by weight of water with 4 parts by weight of boricacid and 5 parts by weight of potassium iodide) (underwater stretching).

After that, the laminate was immersed in a washing bath having a liquidtemperature of 30° C. (an aqueous solution obtained by compounding 100parts by weight of water with 4 parts by weight of potassium iodide)(washing treatment).

Subsequently, a PVA-based resin aqueous solution (manufactured by TheNippon Synthetic Chemical Industry Co., Ltd., trade name: “GOHSEFIMER(trademark) Z-200”, resin concentration: 3 wt %) was applied to thePVA-based resin layer surface of the laminate, and a protective film(thickness: 25 μm) was bonded thereto, followed by the heating of theresultant in an oven maintained at 60° C. for 5 minutes. After that, thesubstrate was peeled from the PVA-based resin layer. Thus, a longpolarizing plate having a width of 1,200 mm and a length of 43 m(polarizer having a thickness of 5 μm (single axis transmittance:42.3%)/protective film) was obtained.

A pressure-sensitive adhesive (acrylic pressure-sensitive adhesive) wasapplied to one surface of an ester-based resin film (thickness: 38 μm)having a width of 1,200 mm and a length of 43 m so as to have athickness of 5 μm. Through-holes each having a diameter of 2.8 mm wereformed in the ester-based resin film with the pressure-sensitiveadhesive by using a pinnacle blade every 250 mm in its lengthwisedirection and every 400 mm in its widthwise direction.

The ester-based resin film with the pressure-sensitive adhesive wasbonded to the polarizer side of the resultant polarizing plate having atotal thickness of 30 μm by a roll-to-roll process, and the resultantwas immersed in a 1 mol/L (1 N) aqueous solution of sodium hydroxide for30 seconds. Next, the resultant was immersed in 1 mol/L (1 N)hydrochloric acid for 10 seconds. After that, the resultant was dried at60° C. Thus, transparent portions were formed in the polarizer.

Example 2

A PVA film having a thickness of 60 μm (manufactured by Kuraray Co.,Ltd., PE6000) was immersed in an aqueous solution at 30° C. for 30seconds (swelling step).

Next, the PVA film was immersed in a dyeing bath having a liquidtemperature of 30° C. while an iodine concentration and an immersiontime were adjusted so that a polarizing plate to be obtained had apredetermined transmittance. In this example, the PVA film was immersedin an aqueous solution of iodine obtained by compounding 100 parts byweight of water with 0.15 part by weight of iodine and 1.0 part byweight of potassium iodide for 60 seconds (dyeing treatment).

Next, the PVA film was immersed in a cross-linking bath having a liquidtemperature of 30° C. (aqueous solution of boric acid obtained bycompounding 100 parts by weight of water with 3 parts by weight ofpotassium iodide and 3 parts by weight of boric acid) for 30 seconds(cross-linking treatment).

After that, the PVA film was uniaxially stretched in its longitudinaldirection (lengthwise direction) at 5.5 times between rolls havingdifferent peripheral speeds while being immersed in an aqueous solutionof boric acid having a liquid temperature of 70° C. (aqueous solutionobtained by compounding 100 parts by weight of water with 4 parts byweight of boric acid and 5 parts by weight of potassium iodide)(underwater stretching).

After that, the PVA film was immersed in a washing bath having a liquidtemperature of 30° C. (aqueous solution obtained by compounding 100parts by weight of water with 4 parts by weight of potassium iodide)(washing treatment).

After the washing, an aqueous solution of a PVA-based resin(manufactured by The Nippon Synthetic Chemical Industry Co., Ltd., tradename: “GOHSEFIMER (trademark) Z-200”, resin concentration: 3 wt %) wasapplied to one surface of the PVA film, a triacetylcellulose film(manufactured by Konica Minolta, Inc., trade name: “KC4UY”, thickness:40 μm) was bonded thereto, and the resultant was heated in an ovenmaintained at 60° C. for 5 minutes. Thus, a polarizing plate including apolarizer having a thickness of 22 μm (single axis transmittance:42.5%), the polarizing plate having a width of 1,200 mm and a length of43 m, was produced.

The ester-based resin film with the pressure-sensitive adhesive havingformed therein the through-holes was bonded to the polarizer surface ofthe resultant polarizing plate by a roll-to-roll process, and theresultant was immersed in a 1 mol/L (1 N) aqueous solution of sodiumhydroxide for 180 seconds. Next, the resultant was immersed in 1 mol/L(1 N) hydrochloric acid for 60 seconds. After that, the resultant wasdried at 60° C. Thus, transparent portions were formed in the polarizer.

The transparent portions of the polarizing plates of Examples were eachevaluated for the following items.

1. Transmittance (Ts)

Measurement was performed with a spectrophotometer (manufactured byMurakami Color Research Laboratory, product name: “DOT-3”). Atransmittance (T) is a Y value subjected to visibility correction withthe two-degree field of view (C light source) of JIS Z 8701-1982.

2. Iodine Content

An iodine content in each of the transparent portions of a polarizer wasdetermined by X-ray fluorescence analysis. Specifically, the iodinecontent of the polarizer was determined from a calibration curveproduced in advance from an X-ray intensity measured under the followingconditions through the use of a standard sample.

Analysis apparatus: manufactured by Rigaku Corporation, X-rayfluorescence (XRF) analysis apparatus, product name “ZSX100e”

Anticathode: rhodium

Dispersive crystal: lithium fluoride

Excitation light energy: 40 kV-90 mA

Iodine measured line: I-LA

Quantification method: FP method

2θ angle peak: 103.078 deg (iodine)

Measurement time: 40 seconds

The transparent portions (before the immersion in hydrochloric acid) ofthe polarizing plates obtained in Examples 1 and 2 had transmittances of90.3% (Example 1) and 90.2% (Example 2), and iodine contents of 0.08 wt% (Example 1) and 0.12 wt % (Example 2), respectively. The iodinecontent of a portion except the transparent portions of each of thepolarizers was about 5 wt %, and hence in each of Examples, transparentportions capable of functioning as non-polarization portions, theportions each having a dichromatic substance content lower than that ofany other portion, were formed.

3. Sodium Content

A sodium content in each of the transparent portions of a polarizer wasdetermined by X-ray fluorescence analysis. Specifically, the sodiumcontent of the polarizer was determined from a calibration curveproduced in advance from an X-ray intensity measured under the followingconditions through the use of a standard sample. The measurement of thesodium content was performed before the immersion in hydrochloric acidand after the immersion.

Analysis apparatus: manufactured by Rigaku Corporation, X-rayfluorescence (XRF) analysis apparatus, product name “ZSX100e”

Anticathode: rhodium

Dispersive crystal: lithium fluoride

Excitation light energy: 40 kV-90 mA

Sodium measured line: Na-KA

Quantification method: FP method

Measurement time: 40 seconds

In the polarizing plate of Example 1, the sodium content of each of thetransparent portions before the immersion in hydrochloric acid was 4.0wt %, and the content after the immersion was 0.04 wt %. In addition, inthe polarizing plate of Example 2, the sodium content of each of thetransparent portions before the immersion in hydrochloric acid was 4.1wt %, and the content after the immersion was 0.05 wt %.

In addition, the polarizing plates obtained in Examples were each placedunder an environment at 65° C. and 90% RH for 500 hours. As a result, ineach of Examples, no large changes in sizes of the transparent portionsafter a humidity test as compared to the sizes before the test wereobserved. The same humidity test was performed on each of polarizingplates produced in the same manner as in Examples 1 and 2 except thatthe immersion in hydrochloric acid was not performed. As a result, ineach of the polarizing plates, the sizes of transparent portions eachincreased by a factor of about 1.3.

Further, surface smoothness near each of transparent portions wasmeasured with an optical measuring instrument “ZYGO New View 7300”manufactured by Canon Inc. The results of the evaluations of the surfacesmoothness (size of unevenness) near the transparent portions ofExamples 1 and 2 are shown in FIG. 6(a) and FIG. 6(b). In Example 1 inwhich the thickness of the polarizer was 5 μm, a step difference betweeneach of the transparent portions (recessed portions) and any otherportion was as small as 0.8 μm or less, and hence a smoother surface wasobtained.

INDUSTRIAL APPLICABILITY

The polarizer of the present invention is suitably used in an imagedisplay apparatus (a liquid crystal display apparatus or an organic ELdevice) with a camera of, for example, a cellular phone, such as a smartphone, a notebook PC, or a tablet PC.

REFERENCE SIGNS LIST

-   10 polarizer-   11 exposed portion (non-polarization portion)-   20 surface protective film (first surface protective film)-   30 protective film-   40 second surface protective film-   100 polarizing film laminate

The invention claimed is:
 1. A polarizing film laminate, comprising: along polarizer; and a surface protective film arranged on one surfaceside of the polarizer, the polarizing film laminate having, on the onesurface side, exposed portions where the polarizer is exposed, theexposed portions being arranged in at least one of a lengthwisedirection or a widthwise direction of the polarizer at predeterminedintervals, and wherein when the polarizer is cut into a predeterminedsize to be mounted on an image display apparatus having a predeterminedsize, the exposed portions are each arranged at a position correspondingto a camera portion of the image display apparatus.
 2. The polarizingfilm laminate according to claim 1, wherein the exposed portions arearranged in the lengthwise direction at predetermined intervals.
 3. Thepolarizing film laminate according to claim 2, wherein the exposedportions are arranged in at least the lengthwise direction atsubstantially equal intervals.
 4. The polarizing film laminate accordingto claim 3, wherein the exposed portions are arranged in the lengthwisedirection and the widthwise direction of the polarizer at substantiallyequal intervals.
 5. The polarizing film laminate according to claim 1,wherein a direction of a straight line connecting the exposed portionsadjacent to each other falls within a range of ±10° with respect to theat least one of the lengthwise direction or the widthwise direction ofthe polarizer.
 6. The polarizing film laminate according to claim 1,wherein the polarizer has a thickness of 10 μm or less.
 7. Thepolarizing film laminate according to claim 1, wherein portions of thepolarizer corresponding to the exposed portions each have a polarizationdegree of 99.9% or more.
 8. The polarizing film laminate according toclaim 7, wherein the polarizing film laminate is subjected to a step ofdecoloring the portions of the polarizer corresponding to the exposedportions while being conveyed in the lengthwise direction.
 9. Thepolarizing film laminate according claim 1, wherein portions of thepolarizer corresponding to the exposed portions comprisenon-polarization portions formed by decoloring the polarizer.
 10. Thepolarizing film laminate according to claim 9, wherein thenon-polarization portions each have a transmittance of 90% or more. 11.The polarizing film laminate according to claim 9, wherein the portionsof the polarizer corresponding to the exposed portions each include arecessed portion having a recessed surface on the one surface side ofthe polarizer.
 12. The polarizing film laminate according to claim 9,wherein the non-polarization portions comprise low concentrationportions each having a content of a dichromatic substance lower thanthat of any other portion.
 13. The polarizing film laminate according toclaim 12, wherein a content of at least one of an alkali metal or analkaline earth metal in each of the low concentration portions is 3.6 wt% or less.
 14. The polarizing film laminate according to claim 12,wherein the low concentration portions are formed by bringing a basicsolution into contact with the polarizer.
 15. The polarizing filmlaminate according to claim 14, wherein the basic solution comprises anaqueous solution containing at least one of a hydroxide of an alkalimetal or an alkaline earth metal.
 16. The polarizing film laminateaccording to claim 1, wherein the surface protective film has formedtherein through-holes, and portions corresponding to the through-holescomprise the exposed portions.
 17. The polarizing film laminateaccording to claim 1, wherein the surface protective film is laminatedon the polarizer in a peelable manner.
 18. The polarizing film laminateaccording to claim 1, further comprising a protective film arranged onanother surface side of the polarizer.
 19. The polarizing film laminateaccording to claim 18, wherein the protective film has a thickness of 80μm or less.
 20. The polarizing film laminate according to claim 1,further comprising a second surface protective film arranged on anothersurface side of the polarizer.
 21. The polarizing film laminateaccording to claim 1, wherein the exposed portions are arranged in adotted manner.
 22. The polarizing film laminate according to claim 1,wherein a plan-view shape of each of the exposed portions comprises asubstantially circular shape or a substantially rectangular shape. 23.The polarizing film laminate according to claim 1, wherein thepolarizing film laminate is wound in a roll shape.
 24. The polarizingfilm laminate according to claim 1, wherein the polarizing film laminateis used for producing a plurality of polarizers each having anon-polarization portion.